1. Technical Field
The present disclosure relates to a bipolar plate for an electrochemical fuel cell. Particularly, the present disclosure is directed to a bipolar plate for a fuel cell made from low cost materials, such as carbon materials.
2. Background Art
Portable fuel cells must meet strict cost requirements in order to be commercially viable. One of the components that contributes a major cost to such cells is the bipolar plate that separates the individual cells.
Bipolar plates serve a number of functions in a fuel cell and have certain requirements. Bipolar plates facilitate the distribution of fuel gas and air uniformly over the active area of the membrane electrode assembly (“MEA”). Ideally, bipolar plates should be gas impermeable and have a suitable flow field design for operation. Bipolar plates conduct electric current from cell to cell and/or to an external load. As such, bipolar plates should have low bulk electrical resistance and low contact resistance. Bipolar plates may also facilitate heat removal from the active area of the fuel cell helping to maintain proper operation temperature and therefore require good thermal conductivity. Bipolar plates should prevent leakage of gases and coolant and be resistant to chemical corrosion. Moreover, bipolar plates should have good mechanical properties including suitable flexural strength as well as a suitable thermal expansion coefficient. Bipolar plates should also have low weight, low volume and low cost.
To get useful work out of fuel cells in the form of a useful voltage, a plurality of fuel cells are generally connected in series. The anode of one cell is connected to the cathode of the adjacent cell via the bipolar plate. The bipolar plate performs the dual functions of gas supply to the active areas of the cell and electron conduction from the anode of one cell to the cathode of the adjacent cell or to the load. Moreover, bipolar plates have many other application specific requirements.
Certain types of fuel cells utilize a polymer electrolyte membrane. These fuel cells can be useful in portable applications. U.S. Pat. No. 6,465,136 and U.S. Pat. No. 6,638,659 are generally directed to high temperature MEAs for use with these types of fuel cells. The disclosure of each of these patents is explicitly incorporated by reference herein in its entirety. Some of these polymer electrolyte membranes incorporate phosphoric acid electrolyte.
Due to the highly acidic environment and the high temperature of operation in such applications, the bipolar plates must be corrosion resistant. Such bipolar plates, especially for portable fuel cells, should be lightweight and also have a high thermal conductivity for heat dissipation. Moreover, the bipolar plate represents a significant portion of the overall stack cost. Therefore, reducing the material and the fabrication cost of the bipolar plate is also important. Thus, there remains a continued need in the art for a fuel cell having bipolar plates that address the above issues. The present disclosure provides a solution for these problems.
These and other disadvantages and/or limitations are addressed and/or overcome by the systems and methods of the present disclosure.